Defensive publication



DEFENSIVE PUBLICATION UNITED STATES PATENT OFFICE Published at the request of the applicant or owner in accordance with the Notice of Dec. 16, 1969, 869 0.G. 687. The abstracts oi. Defensive Publication applications are identified by distinctly numbered series and are arranged chronologically. The heading of each abstract indicates the number of pages of specification, including claims and sheets of drawings contained in the application as originally filed. The files of these applications are available to the public for inspection and reproduction may be purchased for 30 cents a sheet.

Defensive Publication applications have not been examined as to the merits of alleged invention. The Patent Otfice makes no assertion as to the novelty of the disclosed subject matter.

PUBLISHED APRIL 21, 1970 T873,013 PROCESS FOR SOLID PHASE POLYMERIZATION 0F POLYETHYLENE TEREPHTHALATE Charles J. Kibler, P.0. Box 511, Kingsport, Tenn. 37662 Continuation of application Ser. No. 693,769, Dec. 27, 1967. This application Oct. 23, 1969, Ser. No. 868,946 Int. Cl. C08g 17/003 US. Cl. 260-75 No Drawing. 21 Pages Specification Glycol (ethylene, primarily) terephthalate (may include small amount of other diacids) is partially polymerized to amorphous polyester prepolymer melt having an inherent viscosity of about 0.2-0.65 which is cooled rapidly (quenched to a solid), heated at about 120-140" C. to partially crystallize the solid, and particles of the solid are polymerized at about 200-235" C. to an inherent viscosity of at least about 0.6 and at least 0.15 unit higher than the prepolymer being polymerized. The polymerization can be in a vacuum with stirring, or in a fluidized state using an inert gas. The improved polyesters have sharp melting points, and fibers have low harsh count and very few slubs. 

